1. Field of the Invention
The present invention relates to a terminal connector for input and output of electric signals, particularly in audio and video equipment systems.
2. Description of the Related Art
Referring to FIG. 4, a conventional terminal connector, shown generally at 100xe2x80x2, includes an electrically conductive terminal plate 14 mounted on an insulative circuit board 10. A terminal 15 is secured to insulative circuit board 10 by a screw portion 17 threaded through a screw hole 16 in terminal plate 14. A knob 19xe2x80x2, affixed projecting away from insulative circuit board 10 enables screwing and unscrewing screw portion 17 for making electrical connection, as will be explained. Conventional terminal connectors of this type generally have a four-gang or eight-gang configuration.
Circuit board 10 includes four cylindrical portions 11 (two not shown). Cylindrical portions 11 are integrally formed on a first surface of circuit board 10 and surround a part of terminals 15 near the first surface of circuit board 10. Cylindrical portions 11 help avoid lead wire shorts and reduce the chance of electrical contact with a person or an object. Cylindrical portions 11 each have at least one lead wire insertion notch 12 in an outer periphery.
A through hole 13 accommodates adjustable screw portion 17 of terminal 15. Screw portion 17 is centered in cylindrical portion 11. Around through hole 13, a plurality of insertion holes 20 permit insertion of one or more press-in lock pieces 21 and a terminal portion 22 of terminal plate 14 into selected insertion holes 20 to fix terminal plate firmly to insulative circuit board 10. Terminal portions 22 have connective ends formed opposite terminal plate 14 for connecting to a printed circuit board 34.
During assembly, the extremities of terminal portions 22 of terminal plates 14 are inserted into cylindrical portions 11 from above and slipped partially into insertion holes 20. Further insertion of terminal portions 22 requires rotating terminal portion 22 (counter clock wise to the plane of the page) to allow bends 33 to freely pass through cylindrical portions 11 and protrude from a second surface of circuit board 10. As terminal portions 22 protrude through the second surface of the insulative circuit board 10, press-in lock pieces 21, of terminal plates 14, are pressed into the remaining insertion holes 20 for fixture. After assembly, a bottom surface of terminal plate 14 rests directly against a top surface of circuit board 10.
After the integration of terminal plates 14 and terminal portions 22, terminals 15 are threaded into terminal plates 14. Screw portions 17 are screwed into screw holes 16 formed in terminal plate 14. When each screw portion 17 is tightened, a collar 18 of terminal 15 contacts terminal plate 14, and an end portion of screw portion 17 protrudes below the second surface of insulative circuit board 10. After tightening, the end portion of screw portion 17 is mechanically flattened to form a preventive bulged portion 31 and disrupt a continuous helical thread formed on screw portion 17. Preventive bulged portion 31 prevents terminal 15 from disengaging screw hole 16 or from being lost during later adjustment.
Once terminal plates 14 and terminals 15 arc connected to circuit board 10, knobs 19xe2x80x2 are loosened sufficiently to allow insertion of at least one lead wire 32 through insertion notches 12. When screw portion 17 of each terminal 15 is tightened toward screw hole 16 in terminal plate 14, a bottom surface of collar 18 and a top surface of terminal plate 14 sandwich lead wire 32 for electrical contact. A banana plug (not shown) may be inserted into a terminal body 59xe2x80x2, contained within terminal 15, having a plug insertion opening 26 and a plug connection portion 23, for electrical connection. More than one lead wire may be captured this way, and connected to a connector inserted into plug connection portion 23 and/or terminal portion 22.
Referring additionally to FIGS. 5 and 6, insertion holes 20 permit insertion of one or more press-in lock pieces 21 and terminal portions 22 of terminal plate 14 to firmly fix terminal plate 14 to insulative circuit board 10. In FIG. 5, bulged portions 31 expand beyond an outside diameter of screw portion 17, thus preventing disengagement. In FIG. 6, terminal portions 22 may be of different lengths and each respective bends 33 of different curvature radius.
Conventional terminal connectors create several manufacturing difficulties. First, it is difficult to automate the step of integrating terminal plate 14, with press-in lock pieces and terminal portions 22, into insulative circuit board 10. The extremities of terminal portions 22 require insertion in conformity with the curves on bends 33 from above the cylindrical portion 11. Additionally, printed circuit board 34 may have terminal plates 14 with different length terminal portions 22, depending upon production requirements. This difference in length makes automated assemnbly difficult.
Second, the flattening step forming bulged portions 31, described above, needs to be performed after terminal plates 14 and terminals 15 are installed into insulative circuit board 10. As a result, performing the flattening step, during sub-assembly of terminal 15, is inconvenient and increases manufacturing time and cost.
Third, during the assembly of conventional terminal connectors 100xe2x80x2 in general and during the flattening step of bulged portions 31 specifically, damage can occur to exposed terminal portions 22. As a result, manufacturing waste and costs are increased.
It is an object of the present invention to provide a terminal connector where automated assembly of multiple terminal plates into an insulative circuit board is easy.
It is another object of the present invention to provide a terminal connector which eliminates the need for an after-assembly flattening step while providing means for preventing the terminals from falling off or disconnecting from the terminal plates.
It is another object of the present invention to provide a terminal connector having an improved assembly time and a lower defect rate.
It is another object of the present invention to provide a terminal connector with reduced size and smaller footprint.
An insulative circuit board receives a forged terminal and a simplified terminal plate inserted through a through hole and guided by insertion slots, to form a terminal connector. The terminal plate firmly fixes to the insulative circuit board by locking into integrally formed locking steps. The terminal is retained by the snap-in terminal plate and preventive means formed integrally with the circuit board. Preventive means prevents unexpected disassembly when the terminal and the terminal plate lose threaded engagement and eliminates the need for after-integration processing. A guiding means, formed integrally with the terminal, guides the terminal into threaded engagement with the terminal plate when the terminal and the terminal plate lose threaded contact. Guiding means also prevents damage to a terminal plate screw hole and speeds assembly.
According to an embodiment of the present invention there is provided, a terminal connector comprising: a circuit board having a top and bottom face, a terminal plate attached to the circuit board, a terminal having a screw portion engaged in a screw hole formed in the terminal plate, the circuit board having a through hole, into which the terminal is inserted from the bottom face, to which the terminal plate is attached as well, and means for preventing the terminal from separating from the terminal plate when the screw portion of the terminal and the screw hole in the terminal plate lose threaded engagement.
According to another embodiment of the present invention there is provided a terminal connector with preventive means further comprising: a preventive lock portion extended inward from. a cylindrical portion, and a preventive lock retention portion extended outward from the terminal.
According to another embodiment of the present invention there is provided a terminal connector further comprising: an insertion slot provided in a bottom surface of said circuit board to accommodate a bent portion of the terminal plate, and a lock tab integral with the bent piece for locking with a lock step provided in the insertion slot, the terminal plate attached to the insulative circuit board by inserting a bent piece of the terminal plate into the insertion slot provided on the bottom surface of the insulative circuit board so that the lock tab is locked into a lock step provided in the insertion slot.
According to another embodiment of the present invention there is provided a terminal comprising: a screw portion, a minor diameter portion having a diameter smaller than that of said screw portion, a collar, a plug connection portion, and a knob having a plug insertion opening, the screw portion and the minor diameter portion being extended toward one end away from the collar at the center, the plug connection portion extended toward the other end away from the collar, the outer periphery of the plug connection portion being covered with the knob, and the minor diameter portion fitting in the screw hole when the screw portion of said terminal and said screw hole in said terminal plate threadably disengage with each other and the terminal is retained by said coming-off preventive means, the means composed of a coming-off preventive lock portion extended inward from a cylindrical portion and a coming-off preventive lock portion extended outward from the terminal.
The above, and other objects, features and advantages of the present invention will become apparent from the following description read in conjunction with the accompanying drawings, where like reference numerals designate the same elements.